Intelligent Agents: Perceive, Decide, Act — lecture notes
Watch a robot vacuum perceive its world, decide and act — the agent loop that underlies everything from thermostats to AI assistants.
0:001. Introduction
In AI, an agent is anything that perceives its environment and acts on it to achieve a goal. Let us watch one at work.
0:112. A cleaning agent
Here is a simple robot vacuum. Its sensor perceives whether the current square is dirty. A rule decides what to do. If dirty, suck. If clean, move on. Its performance is measured by how many squares it cleans.
0:273. The agent loop
Every agent runs the same loop. Perceive through sensors. Decide what to do. Act through actuators. And the best agents also learn from the results, getting better over time.
0:404. Types of agents
Agents come in levels of sophistication. Simple reflex agents follow if-then rules. Model-based agents remember the world. Goal-based agents plan. Utility-based agents weigh trade-offs. And learning agents improve with experience.
0:535. PEAS
To design an agent, describe it with PEAS. Performance measure, environment, actuators and sensors. For our vacuum, that is squares cleaned, the rooms, wheels and suction, and a dirt sensor.
1:076. Recap
Remember: an agent perceives and acts. Sensors bring information in, actuators change the world. Agents range from simple rules to learning systems, and PEAS describes any of them.
Key takeaways
- An agent perceives its environment and acts on it to achieve goals.
- Agents range from simple reflex rules to learning systems.
- PEAS — performance, environment, actuators, sensors — describes any agent.
- Modern AI assistants that use tools follow the same perceive–decide–act loop.
Check yourself
- A thermostat that switches heating on below 20 °C is what kind of agent?
Show answer
Simple reflex agent — It applies an if–then rule to the current percept.
- In PEAS, what does the “A” stand for?
Show answer
Actuators — Actuators are how the agent acts on its environment.
- Which step comes between perceiving and acting?
Show answer
Deciding — The agent decides which action best serves its goal.
Go deeper
- Intelligent Agents, Environments and the PEAS Framework · The AI Lecture Hall
- AI Agents and Tool Use: LLMs That Act · The AI Lecture Hall
© 2026 Janin A Apurba, CSE, AUST · Advanced ICT Officer, CNRS-UNHCR. All rights reserved. Notes for the animated lecture at https://ai-in-motion.vercel.app/watch/intelligent-agents.html